Method of producing oil from low pressure wells by use of a plunger lift device



Oct. 13, 193.6. H. w. FLETCHER METHOD OF PRODUCING OIL FROM LOW PRESSURE WELLS BY USE OF A PLUNGER LIFT DEVICE Filed Sept. 8, 1934 IN VEN TOR.

A TTORNEYS.

Patented Oct. 13, 1936 PATENT OFFICE mz'rnon or PRODUCING on. mom now rnnssuaa WELLS BY USE or A PLUNGER LIFT DEVICE Harold W. Fletcher, Houston, Tex.. minor to Hughes Tool Company, Houston, Tex, a corporation of Texas Application September 8, 1934, Serial No. 743,279

3 Claims.

My invention relates to the production of oil from deep wells in which the well pressure is so low as to normally raise the oil to a comparatively low level in the well. In operating such wells with the plunger lift apparatus the air or gas pressure necessary to raise the plunger with a load of liquid also exerts a back pressure upon the formation which makes it practically impossible to obtain suflicient head of liquid to 1 operate.

It is an object of my invention to provide an arrangement of the apparatus such that suflicient head of oil can be obtained for successful operation in spite of the pressure of the air or gas.

I desire to extend the well below the level of the producing stratum, and thus by gravity obtain a total head of liquid which by seeking an equal level in the eduction tube will enter said tube in sufiicient amount to produce the desired load above the plunger.

I aim to produce a head of 'oil above me lower end of the eduction tube sufficient to balance the pressure of the air or gas in raising the plunger and its load to the surface.

I the drawing herewith is shown a plunger lift apparatus arranged to carry out my invention and in which:

Fig. 1 is a central vertical section of the upper end of the apparatus, and;

Fig. 2 is a similar view of the lower end of the apparatus; the two sections together showing the complete installation.

When a well is to be pumped, and in which the bottom hole pressure is so slight as to raise but a very low head of liquid therein, I contemplate drilling the well down for a suitable depth below the said producing stratum so as to provide a well hole into which the oil may flow by gravity. In

the drawing herewith such a well is illustrated.

In thus equipping the well, the well hole is extended downwardly below the oil sand I for a depth which is calculated to be suitable for the purpose. This extension is equipped with a casing 2 having a strainer 3 at the level of the sand- This casing extension is sealed to the casing 4, originally set in the well, by a packer or seal 5 in the usual manner. This extension 2 is closed at its lower end and is thus open only at the sand level through the strainer 3.

The casing I has a casing head 6 formed with a flanged support for a nipple 'l which is similarly connected to the flow head 8. The casing head has a lateral port 9 leading to atmosphere or to some point of reduced pressure. The nipple 1 also has a similar port l0 through which gas or air under pressure may enter. The flow head has an outlet port ii for the fluid issuing from the well.

The nipple l is threaded at l2 for connection to the inner pressure tube l3 which extends downwardly in spaced relation inside thecasing and is connected at its lower end to the cap ll having a tubular plug it screwed therein. The upper end of said plug forms a seat for a standing valve l6.

The eduction tube I1 is connected to the lower endof the flow nipple 8 at its upper end and to a va ue casing l8 at its lower end. Said valve casing .Jscrewed within the cap I at its lower end and is thus firmly supported. Said casing has an inner shoulder I! which forms a seat for a stop plate 20 for the plunger. Above the seat are a plurality of openings 2| in the valve casing through which air or gas may enter.

The plate 20 has upwardly directed passages 22 therein for liquid from the well. A shock absorbing spring 23 fits about a lower tubular neck 24 upon the plate and is supported upon the plug i3 so as to absorb the shock of the falling plunger 25.

Said plunger 25 is of usual construction. It has a tubular body with an upwardly flaring passage 26 therethrough. A valve 21, normally supported below said passage upon a. support 23 secured to the valve body, is adapted to be moved upwardly to close said passage. A stem 23 projecting downwardly through said support is adapted to contact with the stop plate 20 and thus move the valve to closed position.

Within the flow nipple is a perforated tube section 30 to receive the plunger and to permit the outward discharge of fluid from the well to the outlet ll. Above the flow nipple is the extension 3i for the eduction tube. This extension may have a gate valve 32 therein and the upper end is closed by a collar 33 and a cap 35. A resilient sleeve 34 of rubber or similar material, is housed in the collar to act as a shock absorber in case the plunger should move too far past the outlet. I provide a plug-closed opening 36 in the cap to be opened when the plunger is to be allowed to move to the upper end of the tube extension.

With this arrangement of the apparatus it will be seen that the oil entering the well through the perforations 3 will gravitate downwardly and fill the lower end of the casing and will lift the valve i6 and rise at least to the level of the'oil sand in the eduction tube. Air or gas introduced under pressure into the pressure tube through pipe ll may then pass downwardly between the pressure tube and the eduction tube and enter openings 2| below the plunger, which will rest upon the plate 20. As the plunger has a head of oil above it, the plunger and its load of oil may be thus raised by the gas pressure to the surface and be discharged through openings 30 and outlet II to storage. The plunger will pass upwardly into the closed extension 3| where the back pressure of gas and liquid will stop the plunger and open the valve 21, thus allowing the plunger to fall into the liquid accumulated above the stop plate. As the plunger reaches the stop plate the valve will be closed and the apparatus will be ready for another cycle of operations.

By the use of the apparatus arranged as shown and described, I am enabled to operate wells which might otherwise be incapable of operation. With the lower end of the eduction tube spaced the desired distance below the producing stratum, a proper head of liquid is obtained and the pressure of the pneumatic fluid is not exerted upon the producing sand so as to prevent its free entrance to the well.

What I claim as new is:

i. A device of the character described including a well casing adapted to be set in a well so as to extend a suitable distance below the oil stratum, said casing being closed at its lower end and perforated at the level of said oil stratum, a pressure tube in said casing, an eduction tube in said pressure tube, a cap closing the lower end of said pressure tube about said eduction tube, a

valve at the lower end of said eduction tube, said eduction tube having lateral air inlets above said valve, a plunger freely movable from end. to end of said eduction tube and means to conduct air or gas under'pressure into the space between said tubes.

2. A device of the character described including a well casing adapted to be set in a well so as to extend a suitable distance below the level of the producing stratum, said casing being closed at its lower end and perforated at the level of the producing stratum, a pressure tube in said casing, an eduction tube in said pressure tube and sealed therewith at its lower end, a liquid inlet at the lower end of said eduction tube, said eduction tube having openings therein above said inlet to admit air from said pressure tube, a plunger in said eduction tube freely movable therein from end to end thereof and means to conduct gaseous fluid under pressure into said pressure tube.

3. A method of pumping low pressure wells having an eduction tube therein comprising extending the well and tube below the producing stratum so as to obtain a suitable head of 011 above the lower end of the tube by gravity, introducing a barrier through said 011 to the lower end of said tube, introducing gaseous pressure fluid into the lower end of said tube below said barrier, obstructing the pressure of said fluid upon the liquid in the well outside said tube, and raising said barrier and its load of oil to the surface.

HAROLD W. FLETCHER. 

